While the play of rookie quarterback Geno Smith and running back Bilal Powell has gone above expectations, the real reason the Jets have found a way to beat teams like the Atlanta Falcons and the New England Patriots is the play of their defense.

That’s been Rex Ryan’s calling card throughout his NFL career, but the Jets suffered a major downturn last year, ranking 26th against the run. They regularly got pushed around by opposing offensive lines. It seemed that the embarrassing play of Mark Sanchez and the offense seemed to permeate the entire team.

There was no reason to think that any aspect of the team’s play would turn around this year. The Jets had brought in a new general manager in John Idzik who had decided to wait one year before bringing in his own head coach.

That way the general manager gets the lay of the land, gets to take the measure of his current head coach while making his list of strong candidates that he can put into action on Black Monday (Dec. 30), the day after the regular season ends.

That’s what the Chicago Bears did after hiring general manager Phil Emery in 2012. Instead of laying waste to head coach Lovie Smith — another defensive specialist — he let him have one more year before he pulled the trigger.

It looked like the Bears had a solid shot at making the playoffs after starting the season with a 7-1 record, but they struggled in the second half of the season. They finished the year with a 10-6 record, failing to make the playoffs, and Smith was fired.

The Bears brought in an offensive-minded head coach in Marc Trestman, and they appear to be improved in that area as the defense has gotten older and vulnerable.

Idzik seems almost certain to follow the same path. These are somewhat heady days for the Jets because they are coming off an overtime victory over the Pats, but it will all go down the drain if they can’t play consistently the rest of the way.

The Jets are challenged the next two weeks by the Bengals and New Orleans Saints, but the remaining seven games are not unreasonable. The Jets have two games remaining against the Dolphins, as well as winnable games against the Bills, Raiders and Browns. The other two games are against the defending Super Bowl-champion Ravens and the suddenly improving Panthers.

The Jets would have a 9-7 record by winning five of their last six games and a 10-win season would give them a good chance at making the playoffs.

If that happens, it will be the defense that leads the way. The front seven has been as aggressive as any unit in the league.

Nose tackle Damon Harrison is a stud on the defensive line. He is getting a push up the middle as he reads the center and controls the gaps. Defensive ends Muhammad Wilkerson and Sheldon Richardson never seem to take any plays off and win a lot more battles than they lose.

That’s why inside linebackers David Harris and DeMario Davis are leading the team in tackles. They don’t have to get away from interior offensive linemen who have attached themselves. Instead, they are free to run, and that’s why they blow up so many plays.